Two Fun Flap Books by Angela Chambers, illus. by Simone Abel, help children learn about opposites and prepositions. In Follow That Chicken! children learn some interesting opposites from the fowl that sits at the wheel of a spiffy blue car. At one point, ""chicken is driving into the shallow water."" With a pull of the flap, ""chicken is driving into the deep water,"" equipped with snorkel and goggles. How Now, Cow? presents a playful cow that teaches prepositions by ""running round and round... whizzing between the trees... and diving onto the bed."" With a lift of the flap, ""Cow is tucked up in bed. Good night, cow!"" An appropriate ending for an active cow. ( Mar.)